Add $LESSOPEN and $LESSCLOSE support (#2444)

src/bin/bat/clap_app.rs

@@ -497,7 +497,20 @@ pub fn build_app(interactive_output: bool) -> Command {
                 .action(ArgAction::SetTrue)
                 .hide(true)
                 .help("Do not load custom assets"),
+        );
+
+    #[cfg(feature = "lessopen")]
+    {
+        app = app.arg(
+            Arg::new("no-lessopen")
+                .long("no-lessopen")
+                .action(ArgAction::SetTrue)
+                .hide(true)
+                .help("Do not use the $LESSOPEN preprocessor"),
         )
+    }
+
+    app = app
         .arg(
             Arg::new("config-file")
                 .long("config-file")
@@ -536,7 +549,7 @@ pub fn build_app(interactive_output: bool) -> Command {
                 .alias("diagnostics")
                 .action(ArgAction::SetTrue)
                 .hide_short_help(true)
-                .help("Show diagnostic information for bug reports.")
+                .help("Show diagnostic information for bug reports."),
         )
         .arg(
             Arg::new("acknowledgements")